I don't think leadership is a nessecary quality for a Chuunin at all. Because, from what the show has shown, the Chuunin are usually not the only Chuunin on their team. So not every Chuunin would have to display leadership qualities, just the ones that are going to be Team Leaders.

It'll be funny when Shikamaru is made leader of his team and Ino has to follow his order, but he'll probably be too lazy to bother giving them.